The first sketches, which were posted on Kosciusko-Morizet's website, envision a swimming pool, a restaurant, a theater, an art gallery, a garden, and a nightclub underneath the subway's arched ceilings.

Rachdi told Le Parisien that he loved the idea of breathing new life into industrial landmarks, citing similar projects in cities like London and Berlin.

The concept is reminiscent of the Old Vic Tunnels in London, a cult-like venue that hosted pop-up art shows and concerts, all housed in a disused railway tunnel underneath Waterloo train station.